Internal-combustion engine.



W. H. PRATT. INTERNAL GQMBUSTION ENGINE.

APPLICATION FILED $11211 2B, 1910.

1,091,703. Patented Mar. 31, 1914 s SHEETS-SHEET 1.

\Nbnese s 5: Inverwbcr";

W. H. PRATT.

INTERNAL COMBUSTION ENGINE.

APPLXUATIUN FUJI SEP'LZB, 1910.

Patented Mar. 31, 1914.

3 SHEETS-SHEET 2.

Witnesses Inventor;

William HZPr'att. b law- JlttJg.

W. H. PRATT. LNTERNAL COMBUSTION ENGINE. APPLICATION FILED SBPI.28,1910.

Patented Mar. 31, 1914.

3 SHEETS-SHEET 3.

Inventor;

o btlg.

William H. Pratt, D W

ltnesses .UNITED STATES PATENT OFFICE.

WILLIAM H. PRATT, OF LYNN, MASSA'CHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPA NY A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Application mes September as, 1910. Serial No. 534,217

Patented Mar. 31, 1914.

To all whom it may concern:

Be it known that I, WILLLnr H. Pnu'r, a citizen of the United .States, residing at Lynn, county of Essex, State of Massachusetts, have invented certain new, and usefulflmprovements in Internal-CombustionEngiifie-s, of which the following 1s a w fi e' This inyention relates to gga ipr .gasolene engines and its object is to providem engine of the internal combustion .class which can be operated either as a founstrolflehycle or a six-stroke cycle engine, the changefroin. one type to the other bein possible wh le the engine is running. this construction is to secure a wider range of economical load for such a motor than is possible by the ordinary method of construction or control;

- The motor hereinafter described can be operated on' thefour-stroke'cycle from full load down to sixtyor even fifty per cent. of full load, while as a six-stroke-cycle engine it can operate from about seventy per cent. of full load down. A motor of this construction will give much higher efficiencies. on loads below one-half than the ordinary four-stroke-cycle motor, owing to the diminution in the amount of fuel consumed per revolution, and to the much better scavenging of the cylinder attainable, by the sixstroke-cycle. This is apparent at a glance, upon comparison of the twocycles, as given below.

Four-sImIce-cycle. lSu-stroke-cydk. 1st strokesuction of charge .suction of charge. 211 compression compression. 3rd expansion .expansion. -4th expulsion of exhaust ..expulsion of exhaust. 4 th ..suction of scavenging air.

. expulsion of same.

It i evident that in the siX-stroke-cycle, the volume of freshair sucked in after the exhaust stroke and then expelled not only leaves the cylinder free from all burned gases, whichwould dilute the new charge, but also cools the cylinder so that the new charge is not heated to so high a tempera-' ture by the cylinder walls. The cooler the charge. the better is the efliciency.

in the accompanying drawings, Figure 1 is an end elevation partly in section, of a single-cylinder gas motor embodying my improvements. Fig. 2 is a side elevation of the same, partly in section. Fig. 3 is aseetion showing the cam, shafts and the timer. Figs. 4 and 5 are sect-ions ofthe,

e P p timer on different planes transverse to its axis. Fig. 6 is a diagram showing the motor operating as a six-stroke-cycle engine. Fig. 7 is a diagram showing it operating as a four-stroke-cycle engine, and Fig. 8 is a slde elevation of a four-cylinder engine embodying my invention.

The invention may be carried out in a. variety of ways, but for the purpose of illustrat on, I have shown an upright engine having a single cylinder 1, provided with awater jacket 2'and mounted on a crank case 8 which atfords journal bearings for a shaft 4 having a crank 5 connected by a rod 6 with the piston 7 in said cylinder. A carbureter 8 furnishes the explosive mixture which is admitted by a valve 9 through an inlet port 10 to the compression chamber 11 at the top of the cylinder, wherethe compressed charge is ignited by 12. A port 13 leads out of the chamber -11 to the exhaust pipe 14, the escape of the burned gases being controlled by a valve 15. In addition to these inlet' and exhaust valves, which are commonly found in all four-strokeoycle engines, I have added a third valve 16 controlling a port 17 adapted to connect the chamber 11 with the atmosphere. This valve is operated preferably by a short lever 18, Fig. 2, and a rod 19. The stems 20 of the valves 9 and 15, together with the rod 19, are provided with springs 21 which operate to hold said valves closed, except as they may be positively opened at the proper times by cams. .It is preferable to use two cam shafts 22 and 23, Fig. 3. On each shaft is a spur gear 24 meshing with a pinion 25 on the crank shaft. In the engine illustrated, the cam shafts are located so near each other, for

the sake of compactness, that the gears 24 overlap, as shown in Fig. L The inion 25 is quite long, so that the cam sha ts can be shifted longitudinally without disengaging the gears from said pinion. The shifting of the cam shafts is for the purpose of bringin into operative position one or the other 0 two sets of cams, one set being arranged to operate the engine on the four--stroke-cycle, and the other set on the six-stroke-cycle. The shifting is effected b a hand lever 26 secured to a rock shaft 2; and rejecting up through a slot in the topof t crank-ease. The rock-shaft has the spark plug two arms 28 bifurcated at their lower no the position shown in Fig.

ends to engage with grooved collars 29 on the cam shafts. When the lever is actuated, the shafts will be slid lengthwise in. their 1 journal bearings. The gears 24 make one revolution for every six revolutions ofthe crank shaft. In the diagrams and 7 they rotate countercloexwise. on run ni on the four-stroke cycle (Fig. .7) the cam 30 on the shaft oro rating the admission valve 9 will have t equidistant swells a b c and the cam 31 on the shaft 23 for operating the exhaust valve 15 also has three equidistant swells d e but these are set thirty de ahead of t ose on the cam 30, as clear y ap ears in Fig. 7. The two valves will thus lie actuated in proper order and at the proper intervals, three times for every revolution of the spur gears, or in other words, once for every two revolutions of the crank shaft. When operating four-stroke-cycle, the air inlet valve 16 remains permanently closed, its stem resting on a cy indrical portion 9 of the cam 32 on the shaft 23, Fig. 2. p

In order to operate the engine on the six stroke-cycle the cam shafts are shifted to 2. A cam 33, Fig. 6, on the shaft 22 having two oppositely. disposed swells h z actuates the admission valve 9 twice in every revolution of the gears 24, that is to say, once for ever three revolutions of the crank shaft. 11 the shaft 23 is a cam 34 having four swells k Z m n arranged in opposite pairs sixty de grees apart and thirty degrees in advance 'of the swells h i. This cam 34 controls the exhaust valve 15. On the cam 32 are two opposite swells 0 p which open the air valve 16 after the swells is m have effected the escape of the burned gases through the valve 15.

The timer or circuit closer for the ignition system includes an arm or contact 35 mounted on one of the cam shafts, as 23, and re volving inside of a casing 36 rotatabl mounted on the bearin 37 concentric wit the shaft 23. Inside the casing is a lining .38 of insulating material concentric with the shaft and on which said revolving contact bears. Two sets of stationary contacts 39 and 40 are mounted in said lining in diiferent planes. of revolution. When the cam shafts are in theposition shownin Fig. 2, the two opposite contacts 39 cooperate with the revolving contact 35; but when the cam shafts are shifted to operate the engine on the four-stroke cycle, the revolving contact is moved with the shaft 23 into line with the three equidistant contacts 40. All five contacts 39 and 40 are connected with the spark pin 12.

T e operation has plained hereinbefore, repeated as follows:

been pretty fully ex but it may be briefly The cam shafts 22 and cycle,

23 carry two sets of cams. and can be shifted longitudinally to bring either set into opentive relation with the valve stems 1-9 and 20. 1

When the change is madefrom four-stroke cycle to six-stroke-cycle, the revolving con-- tact 35 of the ignition system circuit breaker is automatically shifted to coiiperatewith a different set of stationary contacts to accord with thechanged conditions. The casing '36 can lie-rotated on its bearing 37 to retard the spark.

Insaccordance with the provisions'of the patent statutes, I have described the principle of operation of my invention together with the apparatus which I now-consider to represent the best embodiment thereof; but I desire to have it understood that the appa ratus shown is only illustrative and that the invention can be carriedout by other means.

What I claim as new and desire to secure by LettersPatent of the United States is 1. An internal combustion engine having a piston and cylinder, valve gear and electric ignition mechanism for operating it on the four-stroke-cycle, additional valve gear and electric ignition mechanism w ich are put into cotiperative action with the first named valve gear for operating it on the six-strokeand means for changing the valve gear and ignition mechanism from one operating condition to the other.

2. An internal combustion engine having a piston and cylinder, valve gear and electric ignition mechanism for operating it on the four-stroke-cycle, additional valve gear and electric ignition mechanism which are put into cooperative action with the first named valve gear for operating it on the six-strokecycle, and a device which is common to both of said valve gears and to the electric ignition mechanisms for changing over their op-- eration from one cycle to the other at will.

. 3. An internal combustion engine having a piston and cylinder, valves for the cylinder, rotatable cams for actuating a part of the valves when the engine is operating'on the four-stroke-cycle, "another set of cams for actuating all of the valves when the engine is operating on the six-stroke-cyclq shifting means for moving either set of cams into operative relation with the valves, an electricalignition mechanism, arid a device moved by the shifting means for varying the periods of activity of said ignition mechamsm.

4. An internal combustion engine 'plf0.g a

vided with an admission valve and haust valve, a set of cams for operating said valves on the four;stroke-cyole,.an air inlet valve, a set of coma for operat' all three no r valves on the siX-strokewycle, a timing device. and meane for shifting the cams and i-leviee to change from one eyele to the other.

5. An internal eon'ibustion engine pro viderl with an admission valve flfltl an ex haust valve. :1 set of (HIHR for operating Ftll(l valves on the ftlllbfill'()l((-(' \'tl. an air inlet valve. a set of eanls for operating all three 'alves on the .siX-strokeeyele, and means for shifting from one set of eams to the other i at will. (5. An internal (UllllJllHt'lUIl engine prir vitletl with an admission valve and an ex" haust valve, a setof cams for operating said \alves on the four-stroke-evele. an air inlet Valve. a et of eaim for operating all three valves on the sixstrokewcycle. mean .t'or shifting from one set of rains to the other at will. a revolving circuit breaker, and two litl'erent sets of eontaeu eoiiperating therewith in aecordanee with the evele under which the engine is operating.

7. An internal eomhustion engine provitled with an admin ion valve. an exhaust i t'iair-strolw-evele. means for bringing either set of iteviees into operation. alul an ignition lneehanimn for the engine.

8. A n internal eomlmstion engine proville! with an a lu1is ion valve. an exhauq valve. amt an air valve ram n'ieehanisin for operating the three valvea on the sixwwtrohe e vele \vhen aiil meehanism is in a given o sition. lllCtlll for shifting the cam met-ha- Illslll to render the air valve inoperative and to operate the other valves on the fourtrol e-e vele. antl an ignition nieehanisni for the engine.

In \vitne. whereof. I have hereunto xet ns v hand this 22nd day of September. 1910.

W itnesses:

FRANK G. llAl'lII-I. (nannies A. lhnxivnn. 

